In providing power to customers, electrical power utility companies employ a power grid distribution network that includes distribution-line-conductors (which are often referred to as power lines). Typically, difficulties or faults within the distribution network are identified only after occurrences of “events.” These events may merely result in a temporary loss of power for a limited number of customers, but more significant problems may occur.
Protection components and systems are known. “Reactive” components are particularly common. A reactive component is a device or system that is activated or deactivated by a fault event or its consequences. For example, a circuit breaker will open a transmission line as a response to excessive current, thereby protecting power distribution equipment. More sophisticated systems are also available.
Clearly, there are benefits to identifying conditions that precede fault events. For example, if it can be determined that a power line from a power transformer is experiencing intermittent fluctuations, scheduling a replacement of the transformer to avoid an outage event would be beneficial to the utility provider and its customers. Thus, “predictive” components and systems are desirable. Monitoring systems that monitor power parameters of equipment and power lines can provide useful information for the prevention and identification of power distribution faults or events.
Power factor is the ratio of real power to apparent power, and ranges from a value of 0 to 1. This is important to utility companies because power factors less than 1 indicate losses and inefficiencies in the distribution network, costing the utility companies money. Measurement of the power factor on the power lines requires accurate measurement of both the changing current signal and changing voltage signal. Conventional monitoring systems tap into power distribution systems to monitor alternating voltage with direct galvanic connections. Galvanic voltage measurement requires connections to two potentials, one being the voltage to be measured, the other being the voltage with respect to which to the measurement is measured (for example a conductor or contact at ground potential). This typically requires a non-isolated galvanic connection or a capacitive connection with special care given to isolate the voltages present. The non-isolated electrical connection and associated equipment is expensive and expensive to install. Further it does not provide for an easily deployed solution in a wide range of locations along a distribution network. Other specialized monitoring systems are known that mount on the distribution lines without a ground reference for voltage measurement. However, these specialized monitoring systems have been unable to accurately measure changing voltage at the power lines from the surrounding electric field due to changes in weather, traffic, dirt buildup on the lines, construction of or placement of large objects near the power lines, etc. Thus, utility companies must rely on measurement of power factor at electrical substations or remote expensive monitoring equipment, which does not facilitate identification of the specific location along a distribution system responsible for a reduced power factor.